The girl, about 10 or 11 years, was brought to safety Thursday using ropes after crews cut through brush on steep trails to reach her. She had been stranded for about four hours.
State fire officials say she was on a hike with a camping group when the boulder came down and hit her, breaking her femur. Camp staff used two-way radios to report the incident to the camp's main office around 3:20 p.m.
None of the other kids in the group was injured.
Chief Rob Sherman says the girl was spotted 300 feet above rescue crews by a helicopter after more than an hour of searching.
She was taken to Watsonville Community Hospital for treatment.